Reddit mentions of Selected Studies: for Cornet or Trumpet (Rubank Educational Library)

The Arban is a great investment for long-term, often called the trumpet player's Bible, but I'd never hand it to a beginner and tell them to go wild. Too easy to develop bad embouchure techniques playing hard/high stuff or burn out from overly challenging material. Still good to have around, especially if you can have a more experienced player/director pick out specific exercises for you (plus there are old edition pdf's that can be found online for free) but here are some more beginner-friendly recommendations.

First of all, get a trumpet method book. I'd go with whatever your school uses if that still applies to you, but if you need recommendations we use Essential Elements in my district - I like the online practice stuff. We've also used Measures of Success which is also good, and was written by some great composers.

I love this book for beginners. It's got etudes that are more musical and not as boring but are still super helpful. This one is for very early beginners, but there's a second one that jumps up a good bit in difficulty. I like this one a lot - we use it in Illinois for our middle school state festival auditions.

For some more "serious" books that are commonly recognized, Chicowicz's flow studies and long tone studies are good for warmups/tone production, and the Clarke studies are great to get your fingers moving. All of these are a little more challenging and arguably more dry so proceed with caution, but they're excellent industry standards that will make you great.

Finally here's one of my favorites if the earlier etude books were too easy for you. This is definitely more challenging but I love it because it's got studies in every major and natural minor key that are fun and musical, plus some bonus scale stuff at the end.

If you have more specific questions or would like more recommendations feel free to reply or pm me. For now it's getting late and all my trumpet books are out in my car so I can't remember anything else. Best of luck!

Edit: First of all, I format like an old man. Second, I actually carefully read your post, so here's some things to investigate on Youtube beyond just these books: trumpet embouchure first and foremost, long tones, breathing exercises (the breathing gym is a good place to start), and key signatures if you're not already well versed in them - you're gonna see different ones more frequently than you're used to on mallet percussion. Also, please try to find someone to help teach you. There's no substitute for in-person instruction, and a good teacher is going to be able to tell you things in more detail and prevent bad habits before they get their grips on you.