Eli5: How was the first ancient animal to ever step (foot?) out of the water, able to survive breathing air instead of water?

Question

Eli5: How was the first ancient animal to ever step (foot?) out of the water, able to survive breathing air instead of water?

In: Biology

Answer 1

ELI5: Evolution: How could that fish climb out of water and breathe air?
byu/Mahoon85 inexplainlikeimfive

ELI5: The SPECIFIC jump in evolution from breathing under water to breathing air?
byu/MonkeyKings inexplainlikeimfive

etc.