As always in a 5C deck, the manabase is VERY important. it need to be good in order to not get behind your opponents.
I've got 1 5C Deck myself and the manabase works kina fine:
https://deckstats.net/decks/112190/1047892-najeela-warrior-tribe/if you don't stick that much to your tribal as I did, there is still some room for improvement.
The other parts of the deck seems okay for me, even if I would prefere a little more removal, but this is very much playgroup dependant.
agbout Slappy T-Rex hint with
Zendikar Resurgent: yes, that card is very great because it offers you alot of mana and some card draw. But i don't like it that much, because you first need 7 mana to play it. This means that it only helps you in mid to late game, where your deck should outpower your opponents already.
Then about Darksteel Ignot vs
Commander's Sphere: The important question here is the number of (mass-) artifact removal in your playgroup. The Ignot is better if you want/need to play safe, because mana rocks get removed. If your playgroup doesn't care about them, the Sphere might be better, because you can use it as card draw later on.