If you strictly are looking to deal with mono red burn/aggro, you need a lot of life gain. Here are the cards you currently have that are terrible vs mono red:
4 snubhorn sentry (can block basic creatures, vs mono red anything that requires the city's blessing to have next to any use is bad versus mono red decks)
4 Skymarcher Aspirant is ok, there are better choices, it's just another 1 drop creature.
Dauntless bodyguard really not much use vs mono red, these are creatures that support building a board, there are better choices.
4 Conclave tribunal - good card in white weenies, if you want something more effective go with [[ baffling end ]] it removes all creatures of a said type from the board, and is cheaper, 3 mana vs 4 (or tapping potential blockers/life gainers)
5 Venerated loxodon which is prob the worst card in your deck for dealing with mono red, it's not an early game card. Mono red wants to win by turn 4ish, this card is useless until after that point.
My suggestions for adds:
More healer's hawk is fine
4x [[ Leonin Vanguard ]] they will need to burn a spell to remove this creature, which a mono red player will want to do.
2-3x [[ Hunted Witness ]] you get 2 blocks out of this guy. Very useful 1 drop vs mono red decks.
3x [[ Baffling End ]] Already explained why this is useful, if they have more than 1 of any given creature type on the board, or even just the one, it/they are gone for good. They won't have enchantment removal, and if they do, they don't get their creatures back they get a 3-3 basic. Very good for taking out their [[ Electrostatic Field ]] or [[ Runaway Steam-Kin ]]
3-4x [[ Ajani's Primade ]] - not so much for the large creature, but again to prioritize the eating of their spells.
2x [[ Martyr of Dusk ]]
Replace what I said to remove with this list and you will have a very high win rate vs mono red. Lifegain is the most effective counter for mono red anything. Most of these creatures/spells are there to buy you time, which is of the essence for these mono red decks that are everywhere. If you want some late game sort of element so you're not top decking vs top decking you can throw [[ Ajani, Adversary of Tyrants ]] in your deck to bring your creatures back, or buff the ones that already exist.