A lot has changed in iOS 26.
When you write the contact list, I choose to believe that you mean the call list. The contact list has not changed that much, apart from the fact that contact photos are now displayed next to the contacts. If you want to use the familiar look in the call list from before iOS 26, you can change it like this:
1. Open the Phone app
2. Select Calls in the bottom menu
3. In the top right corner, press the round button with the three lines
4. Select "Classic"
Now the call menu will look like in iOS 18, and before. You will also get the Favorites menu back in the bottom line.
You also write that you cannot see your contact photos in your message overview. This feature is otherwise activated by default - but you can check if it is activated here:
Settings > Apps > Messages > find Show Contact Photos. If it is not activated - activate it, and then you should be able to see your contact photos in the Message app again.