Obviously too late to be any help for this jam, but from the main page:

Acceptable use of pre-existing code:

-Reuse of UI

-Reuse of private extensions

-Reuse of short snippets of events (Juice effects, for example)

Not acceptable use of pre-existing code:

-Reuse of an existing project with changed art assets

-Reuse of an existing project with minimal changes

-Submission of a project worked on prior to the jam (We can check)

Pretty sure that what you're describing would fall under that second "not acceptable" point (though if you were to come up with your own Dino Run style game from scratch I expect that would be fine). I feel as though I've seen similar rules for previous GDevelop jams so hopefully this gives you something to go on for the next one.