How can I keep that top bar always open?
As stated in the help topic:
The value of this option specifies when the line with tab page labels will be displayed: 0: never 1: only if there are at least two tab pages 2: always
I also want to keep it because it helps me visualize which window is focused when more than one window is opened
Tab pages in vim are not the same as tabs in other popular editors. If you try to use it that way it might be something you struggle with.
A tab page holds one or more windows. You can easily switch between tab pages, so that you have several collections of windows to work on different things. ... Tabs are also a nice way to edit a buffer temporarily without changing the current window layout. Open a new tab page, do whatever you want to do and close the tab page.