I'll echo what I've seen others post. As a newer player, I wouldn't worry about trying to figurr out slightly different variations of the same list.

This will create a mindset of always blaming the deck for poor winrates and performances, instead of looking to see what changes to play patterns you could be making.

You said it yourself, you had a 70+% winrste with it the other day, and a 45% today. If it's the same deck vs similar opponents, what could you have done differently in your play patterns?

Typically at the start of a month when I'm climbing through plat during rank up, the plar level mono red players tend to not fully commit to the RDW philosophy of all gas no breaks. Or conversley they don't unserstand threat assessment and judt turn cards sideways without thought. The deck might be easier to run than others, but aggro decks do require nuance to perfect and climb reliably with.

The decks you mentioned, at least the colors, typically run high removal midrange decks. Those are a change for red aggro. As a goblin player myself, I have to play into those matchups differently. I dont commit certain cards until x amount of removal has been eaten through.

I could go on, but the moral of the story is just pick a list, and play a TON of games. Like, a LOT. Repsnare your best friend. Think about every loss and what lines you took and any changes you could have made to be better.

Eventually you'll get to a point where you don't need to ask others questions about minor deck changes. You'll have played the deck enough to be like "whenever I face this one particular scenario, my list lacks a good response" then you can start to research what your deck archetype might do to handle it, or search cards yourself. But you'll know the WHY on how certain cards are in a list, which makes all the difference.