First: the same as Marx himself, I am not a Marxist. Then: the personal background of the author is not very important for the evaluation of his/her work.
A lot of thoughts that where written down by Marx are simply perfectly valid today, regardles how he came to that thoughts.
Also: That humans are more than their production value, that they are more than a part of a workforce and more than their conumer value is not realy marxist, its simply a value of humanism as such. Not something that can be taken for granted, but something, that needs to be enforced.
If Marx would have become a simple lawyer and never write any book or manifest, the notion here would still be perfectly valid. The world may thank Karl Marx for having said that so nicely but we did not need Marx to find it out.
btw, marx was a critic of humanism, as an bourgoise idealism, but he was a friend of humans, i would say, but he defintly analysed the capitalism very properly, so properly, that marx is more useable to explain the current situation, then any other famouse thinker i know (except horkheimer&adorno&postone&scholz, but all these build on marx;)
There are not "parts" of mankind. There is only one mankind. And people, who actively made a bizarre fortune by exploiting others and use that money to attack science, nature and human values in order to get even more rich and powerfull, like: the Koch Bros. acting as enemies of all people. Inculding you, fellow homo sapien.