I have thought about using a Lightsail instance. The cheapest one is only $3.50/month and includes 1 TB of transfer and should be plenty powerful to serve up static files.
Or yeah, just use DigitalOcean or someone else. They're pretty cheap, too.
AWS honestly always scared me because of the black box aspect, but I use my single VPS for a bunch of sites with different functions and like having understanding of what's going on there. But any $10-$20/month VPS would be able to host that kind of thing without too much issue.
Another option might be Dropbox. Not sure how quickly their free hosting will crap out if it hits reddit front-page level traffic, but it should be good enough to share here or with your friends or whatever.
Or yeah, just use DigitalOcean or someone else. They're pretty cheap, too.