Learn English – word for “to make humble” with a positive connotation

Both self-abased and humble can be considered as antonyms for arrogant. The difference between them in this context being

Humble - Not showing arrogance in spite of knowing that one is good.

Self-abased - Not showing arrogance because he feels he is not good. (Inferiority complex, may be)

Some other antonyms for arrogant are

Modest - Positive

Shy - Neutral

Meek, Servile, timid - Negative

Of course, whether something is positive, negative or neutral will depend on the context it is spoken, people who are engaged in the conversation, how it is said etc. But I feel this can be considered as a broad classification.

Mentor or Motivator would work as alternative terms. (I like catalyst too)

Enabler picked up its negative connotation from psychologists. In relation to behavioral psychology it refers to someone who assists a person with self-destructive behavior - not just drug use, but addictions or negative behavior patterns of any kind. (Making excuses, assisting in covering it up, obtaining materials, etc). It's not technically a specifically negative term but at least in the US it's almost never used outside of the context of enabling addictions or other negative life patterns.