team recommend?

I don't suppose that you've got a Hans Christian Andersen sitting around somewhere, do you? Though even if not, I think you can definitely make functional teams, especially if you can borrow a Waver or something for support.

Jack/Helena + Chloe + Waver should be able to kill things just fine. Jack could supply stars to Chloe, which helps her do a lot of damage, plus the crits will charge up Chloe's NP super fast, so she can spam that a lot and do super damage. Then Waver is also supplying a bunch of extra NP charge, keeping everyone alive, and boosting damage. Otherwise, you could put in Helena in place of Jack, as she can supply additional NP charge, an arts/quick/buster buff to boost Chloe's damage and NP gain, and she has a bunch of arts cards to contribute to arts chains.

Heracles is pretty easy to toss in anywhere.

And I think that Jack/Helena + Nursery + Waver might be nice in a situation where you might want to AOE a bunch of assassins or something. Jack's stars can help nursery charge up her NP pretty fast, so she can spam it. Otherwise, Helena's skills + arts cards would help charge everyone's NP. Plus she also has her own aoe NP. So you could just have them taking turns mowing down waves of assassins with their AOE NPs.

Though I'm also a pretty new player, so you should take my advice with a grain of salt.

im sure youve pulled a hans at some point as hes a 2 star. jack, hans, and nursery would be a pretty good team. jack would create tons of stars, supplimented slightly by hans who give extra crit damage and that would give nursery rhyme the crit stars she wants for her self modification skill and her an hans would help make arts chains and arts crits to spam their nps. hans also provides tons of healing and possible attack and defense buffs. hes truly ana amazing servant that syngergizes well with those two.

you could also sub in kuro for nursery depending on what class youre facing. i wouldnt use them both because theyd strongly compete for stars.

another strong comp would be heracles, mash, and hans. mash and hans played well will keep heracles alive forever so he can keep doing damage. you could also sun leonidis in over mash for boosting heracles' buster cards.

caesar if you have him could go with jack and hans to make jack the main damage dealer.

helena is sort of a mixed bag. she provides pretty good support, but i honestly think the only thing she has over hans is better stats and the team np charge, but you have such strong crit stuff already that your crit arts cards will super charge your nps anyway.

youre right in that the stuff you have isnt what you see everyone talking about as super meta stuff, but take that with a grain of salt. not everyone has every 5 star. you actually have a very strong combo in jack and nursery/kuro interchangably with plenty of 3 star and lower stuff to fill it out. and obviouusly heracles is always strong

My advice for now would be to make sure you have a max levelled character in every slot possible except maybe saber because good sabers are hard to get. Once you have a whole bunch like that, then think about team building.

Class advantage is in fact enough even upto camelot

let's just get this out of the way, First off, you should search those Servants here in GamePress. This site has good reviews for servants in NA and some of them even have recommended Teammates for servants. AND you'll have an actual idea of what their niches, strengths, weaknesses etc
few team comps are
support = the usual suspects. waver/mash/tama/hans/nero(bride).
Jack-herc-mash
Jack-chloe-support
jack-nursery-support
nursery-helena-support
you should pretty much get the general idea of team comps and how to build them based on the comments here