Does Bitcoin + mixers = Monero?
No. Monero's ring signatures draw on Monero's complete TXO set to create a larger anonymity set.

Monero's method has the disadvantage that since it is unclear which TXO were actually spent, they can never be marked as spent and therefore spent TXO  hardly ever leave the TXO set.

In Bitcoin mixers, you're actually dependent on other users also using the same mixer.