Is it possible to make a jib here?

You could potentially make a wooden lip, and then cover that and the in run with orange construction fencing. You'll have 0 edge control and you'll be falling onto concrete if you slip out, but thatll be the most basic setup that I could see working!

It's doable but not recommend.

Once again I'll drop a suggestion based on whats in my head. Not guaranteed to be a perfect solution but something that might work.

You could build a drop in tower, you'll still need it for speed. Put wheels on the back, lawn mower or something else. Have them off the ground slightly so they don't roll. Then lean the tower back and roll it away. You could have your down section latch on to make rolling it around easy. Frame it out and slip it into hooks. For the flat just lay down some carpet. I would also have a good amount of carpet to unroll around your setup. You don't want to be falling on pavement if you don't have to.

Carpet on pavement is not as soft as grass, but it's not bad, and if wet will slide a bit.

I just don't see you getting enough speed to do much without some kind of drop in. People that have 4+ foot tall ones are still struggling for speed sometimes. Obviously there are exceptions and there are many different materials used and other factors for speed, but I'm just saying. It's very very rare people have too much speed even with a drop in ramp. Without, and without a good hill it's tough.