Here are some of my first levels in SMBX (if most assuredly not my first levels made anywhere), which require the 2.0 Beta 3. The stars here are somewhat opaque optional challenge modifiers rather than alternate paths or puzzles, and are meant for level revisit value in a final product. Said context makes it a little more obvious the SMB3 goal frames are associated with them.
Rite of Spring
The third of five levels in the final project. The first level I made, actually.

Boiling Point
The fourth of five levels in the final project. One point at the end makes a fair bit more sense in the full episode.

Feedback and criticism is always appreciated, of course.