Adam. If want the moon, Neil Armstrong. If u want Mars, i raid from a book sally ride says: the first person to land on mars is alive today. He or she is probably a kid involved in a science project somewhere in the world right now. And its going to be a wonderful day when that kid plants the flag of earth into the red soil of mars. Who knows? She might be talking about YOU!
Well to go away from the bible It would depend on your choice. The first person to set foot on the earth was the first person to learn how to jump. That person jumped and then landed on the earth. If you want an extended period of time then the first person that learned to fly. If you want more than the first person to achieve the return trip from outside our atmosphere. If you want more than go with the first person to step somewhere else, the moon, and return to step on earth.
if you believe in the bible and what it says that is fine but I would ask for proof of ' Adam ' besides a book of propaganda written by men with an agenda......if you believe in science then there is still debate on when exactly what that date might be.....anywhere from 23k to 400k years...depends on how you want to define modern man...now if that person from 400,000 years ago was named ' Adam ' we will never know....they way you worded your question is slanted towards the standard christian answer tho