I have no experience with WP before. I tried to install WP 4.7 and have same problem. Only English was in dropdown list.
I thought WP downloads all translate files automaticall but unfortunately it didn't.
To get languages in dropdown list (Settings > General Settings > Site Language)
you need install translate files to wp-content/languages
directory.
To download language file select version of WP here
https://translate.wordpress.org/projects/wp
than select language.
You will get a page where you can download language file.
For example for wp4.7 Ukraine I have got this page
translate.wordpress.org/projects/wp/4.7.x/uk/default
At the end of the page find Export
link.
Select 'all current' as 'Machine Object Messages Catalog (.mo)'
and click export
Then put downloaded file in wp-content/languages directory.
Open or refresh Settings > General Settings page.
You should see new language in dropdown list.
It is important to download .mo file exactly. I spent a lot of time trying to install .po file.
Also if you linux user and have only .po file you can convert it by command
msgfmt -o uk_UA.mo uk_UA.po
To install translate files for plugins and themes you should to do same things with some difference.
More details you can find here
https://codex.wordpress.org/Installing_WordPress_in_Your_Language
chown -R apache:apache /path/to/virtual/domain
and SELinux giving the correct settings) That allowed me after installation to select another language.