Most gacha games are inevitably going to be pay to win, but given everything is PVE, that doesn't mean that F2P players are hung out to dry. With a few of the right units, a bit of skill inheritance and some hero feathers, you can still make a team that works. Plus, they give out more campaign orbs these days than they used to, and the first summon in every focus is free, so that helps.
They've also got a few decent looking free units coming out soon. Joshua is going to be a tempest trial reward, and he has pretty well rounded stats, decent base skills and a legendary that accelerates special cooldown. Fjorm is a little bit further out but her legendary has distant counter built in, she appears to be defense inclined, and is being handed out for free. So if you felt like getting back into it, those two could probably help you break down any walls you felt you were hitting.