Thanks for posting! Wall decorating in rentals is always tricky. I really like that you’re inspired by plants … have you considered wall planters with (either faux or real … though faux will be lighter) hanging plants in them? Unlike a shelf, which would definitely require drilling, wall planters could be fastened to the wall with Command products or something similar. I think the cascade of vines down the wall could bring such a vibrant, lived-in feeling to your space!
As for your awesome collection of art, it’s definitely worth getting some frames for them! Unless you’re going for a very minimalist look (which usually only utilizes one piece of art or two) with some washi tape or a photo clip, framing your wall art gives it a more finalized appearance. I have a video about gallery walls that you could use to get inspiration for layout! If you’re still not sold on the framing idea, some photo clips could be cool!