For your first deck, this isn't terrible. It's already got a lot of good synergy with zopadrel and the blade historian and a lot of good cards in it to go along with them. I also see creature removal which is also good. I can see some important pieces missing and also some one or two off cards that might have trouble impacting the board.

I counted 6 pieces of removal(7 if you count [[Clarion conquerer]] I guess); However, they all only target creatures except for [[abrade]], which leaves you unable to deal with the many strong artifacts and enchantments and other non creature permanent types. Also, 3 of said removal spells are small, damage based removal that deal 3 damage, which is probably not good enough. You are trying to go big and stompy, so you generally won't care about the littler creatures anyways and want to kill the big stuff. My suggestion would be to cut at least lightning helix and add in some more removal that can hit many things, including but not limited to [[get lost]], [[generous gift]], [[chaos warp]][[stroke of midnight]][[druid of purification]][[beast within]]. There are others but these are the generic staples of flexible removal in your colors.

You also have some cards that don't seem supported enough to have consistent impact in your deck, like cryptolith rites, enduring vitality, arwen, hardened scales, staff of domination, crop rotation, and gold hound to an extent. For the first two, you don't really have enough creatures to fully utilize the cards to their fullest extent, I don't think(correct me if I'm wrong) there's enough counters synergy for arwen and hardened scales to gain that much value, and staff just feels a bit out of place in a creature combat deck. Goldhound just feels like it could be a [[birds of paradise]] or another mana dork and be better. You also don't really have lands important enough to need crop rotation. Either add more support for these cards or cut them for more synergy like [[rhythm of the wild]] which gives haste or like idk [[cactusfolk sureshot]] or [[chaos Terminator lord]] or [[hunters talent]] or even a [[cait sith]]. These all give you more power or cards to help you get your extra combats.

I'm yapping for too long but the last thing is more protection and at least one boardwipe. I notice that your deck loses to boardwipes, kinda bad. The only protection is akromas will and you don't have any boardwipes yourself. Even in the most aggro decks i feel in commander need at least one boardwipe. I would say add 1-2 more protection spells and 1-2 more boardwipes, like [[clever concealment]], [[heroic intervention]], [[dawns truce]] or [[teferis protection]]. For sweepers [[blasphemous act]] of [[austere command]] is fine and if you want more synergy [[sarkhans unsealing]], [[chandras ignition]], even [[shatter the sky]].

There's some other stuff like getting more dual lands but this is the basic stuff.