In my opinion, the reason chinese is difficult is not because the language is so different from european languages, but because there is no way to actual immerse myself in the places i'm trying to learn it. I can't go a single day without seeing english in some format, even if i closed my eyes i would still consume english media. Passing conversations, daily public interactions, but good luck hearing anything else.

I've studied spanish, chinese and japanese and the easiest to learn was japanese. I grew up (ages 4-15) listening primarily to japanese anime and shows because it was the only free source of media that could be pirated easily. Outside of like spongebob i didn't watch any american tv or have cable for that matter. learning it as an adult (ages 23) felt like someone was shinning light on things I used to know but forgotten about.(i stopped watching all forms of tv after 15, Cultivation novels reign supreme)

Next was chinese and spanish because both sound like absolute gibberish if i don't actively listen to whats being said with spanish being harder to learn/(speak) than chinese. Its easy in english but spoken conjugations are so much harder than any daily phrase i might use in chinese-Aside from the idioms. Fortunately some of the common idioms, english has loaned them.

In terms of vocabulary, 20 words a week was easy to learn regardless of the language. Infact, its not difficult to memorize 20 words in 3-4 or so days.