moving through a 2D platform/collider

Hi, practically new to Unity (been messing around with level design, making tile sets, characters, etc), keep getting lost in the workings, of it.

Anyway, my experience is low, and I need help on a 2d sidescrollin platformer. It’s early stages, I have the level layed out in bare form, the literal ‘ground’ work. bad Pun…
My issue is, I designed it so that finding the path isn’t straightforward, with collapsed bridges causing the player to to go up and over, problem is… I need to be able to pass through solid objects, upward and sidewards, but not down, so I can literally jump up through to the next platform.

Any guidance would be appreciated.

I have a lot to do just to finish the test level, and there is a learning curve.

FYI, forgot to mention. I ised the platform collider, so I can go UNDER it, but coming from the sides is the issue.