At least 50% of players go allin during the beggining of freerolls with almost any hand for some reasons:
1. They have nothing to lose, only win, they think that going all in with anything at the start improves their chances to win (it doesnt)
2. They are impacient and want the money now, or nothing. They dont want to spend hours playing a calculated and quality poker.
3. Amateur players tend to gamble more, and rely too much on luck, they are playing just for fun and want to win quickly.
With that in mind, if you want to go deep in those tournaments i would suggest you to play very tight at first, dont call any all in during the first 10 minutes, just if you have a premium hand like AA, KK, QQ, AKs.
After you pass though the all ins phase, then you can start trying to steal blinds, having a postflop action and playing real poker. Try to take those advices into consideration and tell me if you do better or worse. See you at the tables