Good lord your roster is huge for your level. You really need to pick a focus and stick to it if you want to climb in Arena.
Let Phoenix go for now. Come back to them later. You've got enough Rebels in process to get Palp if you focus on them.
Part of why you're struggling in Arena is your toon levels. Not as important as stars and gear, but still needed. Focus your credits on your Arena team. Get more credits with credit heists, which means Scoundrels.
Stop with Jyn. Stop with the freaking Jawas and be content with health mods for now. Get a competent squad first.
Who to farm:
Cantina nodes: Finish Lando, then finish Wedge, then think about TFP before Phoenix because dark side pilots are important.
Cantina store: Finish Boba, then start on Chopper since you'll do Phoenix eventually
Squad Arena store: Finish Leia, then choose between Tarkin or Ackbar. You need a fleet commander. Tarkin will get you Zeta mats faster. Ackbar will keep your ship building credits in steady supply, and he'll round out your Rebels. In your situation, I think I'd abandon the idea of Zetas for a while and stick with Ackbar. You can work on pilots later.
GW store: Cad Bane. You need another scoundrel for Credit Heist.
Guild store: same thing, you need 5 scoundrels, so go for Dengar. In the rare event of extra credits, gear.
LS/DS nodes: Chewie to 5* for Credit Heist. Then look into pilots, you'll need them.
Guild Events store: stop spending currency here. Save it for gear. You'll need gear more than a weak-sauce undergeared Wampa.
Fleet store: SHIP SHARDS. Focus on Biggs X-Wing, Wedge X-Wing, TIE Fighter, TIE Advanced, and Slave 1. You can start farming Ghost and Phantom II when you move on to Phoenix, somewhere down the road.
Wedge, Biggs, Lando, and Leia, fully starred, geared, and leveled will help you move up in Arena. Use Boba as your fifth.