Why is our new console not showing the same content on both profiles

The main account would need to set the new console as their Home. https://support.xbox.com/en-US/help/hardware-network/console/my-home-xbox

" If the second player is on the same console that it was downloaded to then he can access the game any time he likes."

If this is the case, then why is the second profile on my console not able to access any of the content I have saved (Main Profile) on the same console. DRM has been transfered to the new console, and content in question has been "Re-downloaded" to said
new console.

If they're both on the same console, you can play the content on either account. If you want to use both accounts at the same imte, you'd have to use the profile that downloaded the content on another console and be signed into Live.

A little confusing but both. The Console the Content (any Content, Game, Game Add-on and such) will have a License tied to that Console for any Profile. But the Content must still be there to use and the License must be up to
date. The Profile that purchase the Content will always have Access to that Content by DL'ing it again at anytime via the Download History.

You can simply DL everything again (at no cost provided it is with the same Profile that purchased it) on any Console. To remove the License from any prior Console (Console ID) you can complete a License Transfer. This removes the "old" License from the prior
Console and adds it to the "new" Console after the Content is DL'd again (and the License Transfer). With the License on the "new" Console (and Content as well), any Profile on that Console will be able to play that Content.

Hope that makes sense.

As long as you're using the same console, then you can access the content on both accounts.

When you purchase content it's tied to the gamertag that purchased it as well as the console it was purchased on. That console license is what allows all profiles to access content on the same console.