It's not about influence on humanity. It's about scholarship.

Marx was a significant and influential economist. Some of his predictions have panned out; others haven't. A lot of his insights are extremely important, and are accepted by even the most hardcore capitalists.

He wasn't particularly thrilled about his "influence". His work wasn't so much "misinterpreted" as just plain co-opted to mean something totally different. He supposedly said, “If anything is certain about me, It is that I am not a Marxist.” The quote may not be authentic, but it accurately reflects that fact that the vast majority of "Marxists" don't appear to have read his work.

And that also holds true for the vast majority of critics. Most of the things commonly attributed to being "Marxist" are just plain false.

His ideology may have been ill-conceived but he was an incisive historian.