Grammarly is misparsing was...helped as a passive. The actual error is a subtle matter of punctuation. You have listed your three characteristics as
... was kind, compassionate, and always helped others.
This construction leads a literal-minded "reader" like Grammarly to believe the three characteristics have the same syntactic role, but this is not the case: the first two, kind and compassionate are adjective complements of was, while helped is not an adjective but a new verb, unconnected with was.
You can eliminate this reading by saying:
... someone who and
always helped others ...
... someone who was kind and compassionate and always helped others.
Gustavson's alternative phrasings, which preserve the list construction at the cost of changing the words employed, are arguably better if the new words preserve your meaning.