Internal backlinks ?

#1 site has 630 internal and no external backlinks at all. Domain authority is 23/100 and page 17/100 analyzed by MOZ with PR 2 and Domain Age 1.1

How important are internal backlinks ? Will it be hard to rank against site like this? Found few articles about internal backlins but still in doubt so tho it would be good idea to ask here.

internal links still do help, but external links are the major factor. Try getting external backlinks to your site

With internal backlinks, this not only passes relevant links but also helps Googlebots to search the site, causing it easier to index. Plugins like YARP for Wordpress can help with this by putting relevant posts at the bottom of all posts.

According to me the internal links helps a lot and we must give same priority to each and every link