Well, Black Adam's powers came from a combination of ancient magic and a specific ritual. This gave him extraordinary abilities like super strength and flight.
Kraven's powers come from a mix of factors. He experiments on himself with special serums and constantly challenges himself in the wilderness to develop superhuman abilities like superior reflexes and acute perception.
Deadpool got his powers through a messed-up experiment. His body was subjected to a procedure that gave him superhuman abilities, but also left him scarred and crazy.
Spiderman gets his powers after being bitten by a radioactive spider. This bite gives him enhanced strength, agility, the ability to climb walls, and a 'spider-sense'.
The Hulk got his powers through a gamma radiation accident. Bruce Banner was exposed to a huge dose of gamma rays, and that's what transformed him into the Hulk when he gets angry.