Most filetypes (like
python) in Vim come with a syntax that defines highlight groups (see them via
:highlight python<C-d>). These particular groups (e.g.
pythonFunction) are then linked to a set of default groups (
:help highlight-groups, e.g.
Identifier). A colorscheme then provides combinations of foreground / background color and/or formatting like bold and italic (separately for terminals, color terminals, and/or GVIM) for the default groups.
Plugins are also encouraged to link to existing default groups; after all, these adhere to the user's preferred style and will work under whatever conditions (low-color / high-color terminal / GUI, bright / dark) the user has. However, some plugins either provide functionality that has no existing related concept in Vim, or they need a highlighting that is relatively independent of user choices (like red / green for test results; those should always look red / green even if the user prefers bluish hues).
So what you see is that Lightline plugin not linking to the default groups. That plugin should use
:help :highlight-default, so you can override its custom definitions (with greenish ones) with
:highlight LightlineLeft_replace_1 ... in your
~/.vimrc (you can always overwrite them later, e.g. on
VimEnter). Yes, that's a lot of definitions there (but apparently mostly combinations of a few base colors and text attributes, and you want just green, anyway), but this needs to be done only once, for this plugin and maybe a few more.
Alternatively, you could employ meta-programming and go over all
:hi definitions after Vim startup (so plugins have added their definitions) and change them to green.