Since the rules let you use pre-made and purchased assets, here's a free one you can drop in today: a 16x16 top-down town tileset with one street, a cafe interior and an animated player character. It's just PNG sprites on a 16 px grid (1x/2x/4x), so it works in GDevelop like any other sprite sheet, no engine-specific setup needed.

Link: https://aquumgifts.itch.io/cozy-town — the Lite above is the free download; the same page also has a Complete with the rest of the town (more interiors, more characters, the full street) for anyone who wants it, and both are free for commercial games too.

Good luck with the jam :)