My Inner Fish Reflection

This video series was about how us humans evolved from being fish to what we are now. Though we might not exactly look like them, we share many characteristics with them. The first question I would like to elaborate more on is: "Even though we don’t look much like fish what are some things that we have in common with fish? How does this give evidence for common ancestry?". Our hands came from fish. There is a specific gene that starts the development of hands; this gene was found first in the fossil of a fish, thus we, who have hands, have evolved from fish. My question though is could there be an organism that had that gene earlier than fish? The second question I would like to elaborate more on is: ""How and why did hair first evolve?". At first, hair evolved as whiskers but later on they evolved all over the body, providing organisms with warmth. With this I also have my own question: What would've happen if hair were just whiskers and never evolved to cover our body?