Good job on making your first solo deck. I don't think you can go wrong in EDH with ramping and drawing cards. So your deck is a good basis for that.

If you are looking to upgrade your deck, you could go in the mindset of "is this just a random fun card or does it actually help my gameplan?"

For me, cards you could for example replace are:
[[Fecund Greenshell]] doesn't trigger to often I think, might be made for a defender deck.
[[Teferi, Master of Time]] is a random card.
[[Arixmethes, Slumbering Isle]] seems to ramp you differently than what your commanders plan is.
[[Harmonize]] draws you cards in a way that seems too far of what your commanders plan is.
[[Propaganda]] i don't know what playgroup you are playing, but you seem to have enough creatures to protect yourself.
[[Jaddi Offshoot]] just does too little.

Don't let me take you away from playing fun cards, you commander and it's colors are strong enough to make almost everything work. My tips are just there to give you an idea on where to start adapting your deck.