Are you for some reason concluding that each atom required its own supernova?
No wonder you're running a bit short.
No, as you indicate, each atomic nuclei was formed in "a" supernova (according to current theory) but many x 10 ^many were formed in each of the ten layers of the many x 10^many superstars that were reacting to fuse elements up to iron56. Each layer is deeper, at higher pressure and temperature, and creates heavier elements from fusion in turn. Before the supernova, H -> deuterium, tritium and He layer is at the outside, and Fe at the inside.
Then, each/some/many/most/all of these manyx10^many superstars went supernova at nearly the same time to produce the elements past Fe56 in the "compression zone" of outgoing fused elements: again, the same supernova can create many tens of trillions of element nuclei: but, if the resulting explosion is symmetric, then only the few elements that are headed in the right direction get to our (eventual) planet.
The closer the supernova's are together, the greater their angle of incidence, and the more likely their expelled residue will get to our planet. The faster the first generation of stars condenses, compresses, and goes through its fusion cycle, the closer it will be to us - if the universe is expanding as theorized.
But, I've never seen a justification (calculation/prediction/article) explaining either "why" the first stars are different than today's (billions times more massive ? Why?) or reacted faster than today's stars: going through in tens of years what now takes thousands or millions of years.