It's easy to see you're 15 lool...
Anyway, you don't necessarily need to be fast, but ofc is good if you are, great advantage... I think the main attributes are to have a good ball control and pass well... Your movements without the ball are also important, need to be in the right place to stop the opponent or to receive a pass...
then there are many skills/attributes like crossing well, free kicks, skills with the ball, influence, long shot, finishing, etc... Play football manager and you'll know