UPDATE 1 - STRONG FORCE
If particles also are the product of their interactions, if their properties or identity can change if they're subjected to extreme conditions, then the question is whether we can infer from collider experiments whether baryons (protons and neutrons) are built out of quarks, or if we only create quarks as they collide.
That QED treats the proton as a fundamental, rather than a composite particle, but nonetheless can predict experimental results to an extreme accuracy, indicates that quark properties are not separately observed until the colliding energy is high enough.
If a particle only exist if and when its presence is expressed in identifiable interactions, can be observed or inferred from effects, then quarks may very well appear only in the extreme conditions at high energy collisions and other violent events like supernovae.
In that case we cannot say that baryons are built out of quarks.
If particles have to create themselves out of nothing, without any outside assistance, and have nothing to know with how to go about creating one another, then they'd hardly pop up in a flash with all properties fine-tuned to the last detail as the Big Bang tale has it.
Instead, we may expect a trial-and-error process: whatever combination of particles, properties, exchange frequencies, mass ratio's, spins and kinds of behavior works in certain circumstances survives, as long as these circumstances last.
Though as particles create each other, they also create the environment to prosper in, once they master the trick to keep existing, they cannot but keep contracting, evolving in steps, through many detours, eventually to objects of ever-increasing mass density.
Every step towards a denser particle configuration further reduces their freedom to act as they like: if particle properties, exchange frequencies are to survive, then destructively interfering frequencies (or associated virtual particles) must be got rid of, radiated away.
As their conditions change as they evolve, they have to adjust their behavior, properties or identity to fit the new conditions they themselves create: as an ongoing contraction to ever-increasing density may require the destruction of earlier, less dense configurations, this evolution can proceed in violent starts and fits as in supernovae.
The conclusion is that quarks and the 2nd and 3rd generation particles of the Standard Model then aren't necessarily the bricks all matter is built out of.
Their self-designed environment then is an ecosystem which by favoring the creation of identical particles, guarantees a continuous, inexhaustible supply of virtual particles which as they keep contracting, eventually will become real ones, 'educated' as to how to act, what frequency to oscillate at by interacting with their real counterparts.
If a real particle by colliding with its virtual sibling (virtual in this context meaning that it hasn't yet got its frequency right) can decay into a virtual one, promoting the virtual one to a real one, then this is a two-way equilibrium reaction.
This, by the way, begs the question whether this kind of virtual particles form the non-baryonic, so-called 'dark matter' which causes the observed unexpectedly high velocities of hydrogen gas in large orbits about galaxies, a velocity which might also depend on the definiteness of the galaxy's mass center.
However this may be, as the energy of virtual particles can have all values, their transition to real ones doesn't leave a recognizable footprint radiation, unlike the H H = He reaction, which likewise is an equilibrium reaction.
To the right, this reaction seems to preserve, to secure the existence of hydrogen, as if without the existence of helium, it might decay any time into protons and electrons.
If particle species are to create one another, then they must find those frequencies and those (discrete) kinds of behavior which sustain their energy exchange -somewhat like how when a piano key is pressed, other strings begin to resonate at related frequencies.
The difference is that in our 'piano-universe', no key is pressed by some outside hand: the piano, its strings only take form as they start to resonate -which is not unlike the Munchhausen tale of the man who pulls himself by his hair out of a swamp.
As the frequency particles exchange energy at depends on their distance, velocity and spin, to keep 'resonating', to maintain their exchange, requires their distance and spin, for example, to be restricted to certain values, to be quantified, so they can absorb energy by leaping to another distance or spin state rather than change their identity.
The freedom to deviate from the ideal frequencies, distances, spins etc, then would be determined by the interval within which they are stable particles.
As the breadth of an energy interval, its indefiniteness is smaller at higher energies, particles have less freedom to deviate from a more strictly prescribed behavior as their (rest) energy is higher.
If when two particles are nearer, their universes overlap more precisely so look more exactly the same, then their properties converge as their distance decreases.
To keep contracting, to form objects of a greater density then requires particle to become more identical -which agrees with the observation (blackbody radiation) that there are increasingly more energy levels to occupy per energy interval at higher energies.
The higher their energy, the more decimals it takes to express differences between them, the more they become identical, the less freedom they have to behave as they like, the more rigid, the greater the inertia of the object they form, the more it is frozen in time.
The result is that particles don't evolve from one generation to the next, to ever more exotic species or, but that instead they loose more individuality, more freedom as the mass density of the object they're part of increases: the higher the density, the more identical, the less interesting they become.
If the (rest) energy of a neutron is higher than that of a proton and much higher than that of an electron, and it repeats in every cycle all rates of change up to the level corresponding to the neutron state, then it periodically, in every cycle for a short time is a proton as well as an electron.
The neutron then runs through all lower-energy identities, be it that it is for a shorter time a lower-energy particle as its rest energy is higher, so it is far more like a proton than it is an electron.
Neutrons and protons then can knit each other to atomic nuclei by exchanging electrons, by alternating their identity, their distance, spin and motion adjusted in such a manner that, within a large but limited temperature scale, their resonance is preserved.
This is why a neutron outside the nucleus environment where it can less easily maintain an exchange at the frequency corresponding to its neutron identity, decays into a proton and an electron, an electron which then becomes a more autonomous particle.
If the force between particles is as much the product as the source of their interactions so a force cannot be either attractive or repulsive, then we don't need the so-called 'strong' force to overcome any electric repulsion between the baryons in atomic nuclei.
That most atomic nuclei are very stable is because the bonds between their baryons have been forged in a very hot smithy, so it takes a high energy to break them up.
If in high-energy collisions, baryons fragment in groups of frequencies we associate with quark pairs and trio's, then the observations ('asymptotic freedom') that, unlike other particles, they seem to attract each other more strongly as they are farther apart and hence cannot be separated, may have another explanation.
The problem is that we have decided that the charge of quarks has a constant magnitude and sign, so we derive their interaction distance, the range of the so-called 'strong' force, from the energy of the interaction assuming their charge to be the source, constant.
However, if the force between them cannot be either attractive or repulsive, if their interaction energy determines their distance and vice versa, if we cannot determine one independently from the other, then we cannot assert that their attraction increases as they are farther apart.
Alternatively, if we create quarks by colliding baryons, then the quarks within a newly created pair or trio mainly exchange energy within that pair or trio: the pairs and trio's recede far too fast from each other to set up a significant energy exchange between the pairs and trio's.
The consequence is that the interaction energy between the quarks of a pair or trio becomes almost independent of their distance within the pair or trio, hence they seem to be confined within the pair or trio -before they reassemble into ordinary hadrons, as their quark properties vanish and their individual existence is dissolved.
Quarks, then, are not the building stones of other particles, so baryons aren't composites but are fundamental particles which only exist within certain conditions.
It may come as a disappointment that QCD describes particles which aren't very useful or interesting in the scheme of things, to understand nature's mechanics.