what is your question here ?
just source code sharing not a question
this might be a bad place for self-promotion
code seems to be straight up copy of a work by Ronan Collobert (collober@idiap.ch) from 2003–2010, available from https://www.idiap.ch/~odobez/human-detection/install.html
preinstall opencv 3.4.16 to /opt/opencv
Programming Guide: opencv and dlib training
the blog post by OP, linked in the readme, claims to have been written in 2013, but it references major versions of OpenCV that didn’t even exist yet.
looks very fraudulent to me.