Clerics are the most useless class in the game right now. What little combat healing you need can be provided by potions, food, scrolls and items. As for most buffs; another attack/spell action would have benefited the party more than the buff in most fights anyway (sure, bless is nice to have but not a must at all).
This might change at higher levels but at least for the first four levels the only reason to even take Shadowheart is for RP purposes, so need to be worried about having to take her..
Except guiding bolt and cause wounds are some of the most damaging low level spells in the 5e (and in this game as well.) Guiding bolt also gives advantage on the next attack, which possibly makes it the most powerful level 1 spell, competing with magic missile. Combine that with the fact that clerics can wear medium armor, can use simple weapons and shields, and get a better hit die than most casters, I'd say that you're severely underestimating clerics and they are far from "the most useless" caster. I'd argue they are (one of) the strongest in the 4 levels we get to play with.
