This is a great question and the answer is a bit dependent upon other factors in your life. Presumably you earned less than $400, not a lot, although you should be proud. To me it boils down to how can we change that into "life-changing money"?
Putting it in a Roth is a great idea and certainly not a bad one. For every $100 you invest in a Roth it will grow to about $2,400 in today's dollars in 47 years (when you are 65). A good idea, but not really life-changing money.
Some would be far better served to put this money in a simple savings account. The most important thing they could do is increase their lifetime earning potential. That might mean going to college, or obtaining a skilled trade. Scholarships can go away, or not provide for all anticipated needs so protecting against that those negative events is the best way to transform this into life changing money. Income is the highest correlation to becoming wealthy according to The Millionaire Next Door.
Some would advocate putting into a Roth anyway as contributions can be withdrawn. I would not do this as there is a 5-year holding period and presumably this person would be out of college by then.
I don't think that is you, however, Roth is probably best. You already have college savings and presumably a very supportive family. Not everyone has that, consider yourself blessed please. Yes, you can only contribute earned income.
Great work on all including earning some from a summer job.