If I upload my photos to the iCloud Library do my original photos on my MacBook Pro remain?

Yes they do. See:iCloud Photo Library - Apple Support

Note that if you open Photos on your Mac and go to Preferences and click iCloud at the top of the Preferences window, there are 2 options: "Download Originals to this Mac" and "Optimize Mac Storage." If you choose the optimize option and your Mac is low on storage space, then the originals may be replaced with smaller optimized versions.