freerolls have a lot of variance, especially during the early all-in stages where everyone is jamming / calling jams with very wide ranges.
you should still play the very top of your range during the early, all-in stages of freerolls. something like 1010+, ak because they'll still do well overall but it's going to be high variance. for example, aa vs 8 opponents who play a 100% range is only winning 25% of the time. you still have the best
equity preflop but you still lose 3/4 times on average. however, when you do hold, you win a big pot and your (hopefully) deep run will make up for the times you bust out.
don't worry about playing marginal hands like j10s, kjo, 33, etc unless you can see a flop cheaply. you don't want to be calling all-ins with marginal hands because you aren't winning enough times to make up for the losses and you'll likely find much better equity spots to get your stack in later in the freeroll. you also don't need to push with anything less than the top of your range in the early stages because you're likely getting called and you want the equity advantage.
if you need to fold everything for the first few blind levels, until the all-ins die down, do it. you'll still have a stack to play with and you can still do very well.