Thanks I managed to get a 5star unit with my 30 summons. I hope amarintha is good not sure how much rerolling I wanna do
Amarintha is a better late game unit than a starter unit, IMO. She's an excellent "support/DPS". She's also a pretty amazing farming unit, too. But as Nyx said, not as good as Sez/Vild would be. But imo, she's better than those two in late game content. Ken is, imo, the best possible pull though, he's really good early game, he's a monster late game, he's a tank and DPS in one, and brings ridiculous debuffs (Stun, Defense down, Attack down, Burn..). He's not a great farmer though.
What makes Amarintha shine is another strong DPS in the group. She pairs really well with most other DPS, and in that
composition (2 DPS), she's one of the stronger DPS but on her own she's only "okay". So for a starter she's not great (You also need a lot of Mola to build up her burn rates, because burns are really important on her.) At Max enhance she can do Fire Pillar-->Cata, and do some nice burn damage plus put up the unhealable debuff. But Mola's are like the most difficult resource to get in the game, so meh.
So it really depends on if you got strong 4 stars imo. Did you get any 4 star DPS? And the one healer I think you should reroll for if you didn't get is Angelica, she is massive for beginners, she'll have more of an effect on you being able to do difficult content than any DPS will. So if you got Angelica, and a decent 4 star DPS, I'd stick with it, but otherwise, try for a reroll. (A lot of the 4 star DPS do as much, or more damage than 5 stars--5 stars just usually bring more utility. But for the start of the game, 4 stars tend to just as well.)
Also, as Uriel mentions--try to grab as many copies of Sol as you can from the special event. Burn up that mountain of free energy going for him. He's an AMAZING unit, not just "amazing for a free unit"--he's amazing in general. If he was in the summons, I'd spend bookmarks on him no problem, he's that good. (I know that's super rare for Gacha games, but seriously, he's incredible. IMO he's actually as strong or stronger than the limited summon units in the collab.)