All at once:
A) particle physics
B) chemical table of elements
C) light, which after 300K-ish years cooled (the volume of the universe expanded) enough for matter to form.
The full chemical table only showed up when neutron stars collided – ordinary supernovae of second or third-generation stars didn’t reach the necessary energy densities to go more than part-way up the table. Neutron stars produced all of the heavier elements – and likely some we haven’t even made in the lab yet. The reason those didn’t stick around is that their half-lives amount to microseconds at best.
Note well that particle physics is carefully tuned. It’s full of what appear to be arbitrary values —
[[the ratio between matter and energy that determines the speed of life, the relative strengths of the four major forces, the relative mass/energy values of each quark, muon, boson, and so forth]]
—which have to have these odd-seeming values, else stars would not for form, or supernovae wouldn’t actually make many of the lighter elements, or colliding neutron stars wouldn’t actually make all of the elements we see today.
Note also that the chemical interactions between the various elements make it possible that DNA will actually work, and in fact that biochemists are beginning to see evidence that, once a cell ‘happens’ life practically leaps forward.
Think of the provision in creating the universe, such that it would not only be complex, but would be ideally suited for life.