BustedChops I'm a comeback player too after 20+ years. If you are like me and just playing for enjoyment find some tunes you like and know. My sight reading also sucks and I'm slow at figuring out rhythms etc. so I started with some Beatles songs, Danny Boy, Scarborough Fair and a number of easier pieces. I also transposed some songs down to keys I could play in until my upper range improved. I hope to one day play last seat 4th trumpet in a community band.
There is a ton of free music on the internet. Don't just look for trumpet music. I'm playing a nice version of Greensleeves written for lutes. Fingering charts, arpeggios, scales and the like can also be found, for free and they aren't as daunting as Arbans for the casual comeback player. IMHO