I think you have a fundamental misunderstanding of the implications of GPLed software.

If you incorporate GPLed software into your own software - that is, copy the source code - then your work is considered a derived work and is also under the GPL.

Software that is LGPLed can be linked to without making your application under the GPL itself. This includes things like glibc. (The "L" in "LGPL" used to stand for "Library" but now it means "Lesser.")

Finally, if you use GPL software to produce your own works, there is no effect. So using git to manage your own source has no impact. Same with using gcc to compile your source.