Beginner strength training

I would suggest focusing on compound moments that work more than 1 muscle group at a time.

Yep.

As a beginner, I was told to make sure I did deadlifts, squats and bench presses.

I also did
-pull ups (beginners can do variations eg assisted, toes on chair etc),
-dumbbell bent over rows and
-overhead shoulder presses.

Twice a week.

Definitely saw improvements in physique and strength, the trick being to keep reps low and volume high - 3x6 (the final repetition must be hard enough to mean you've really got to work). So for newbies I'd recommend just those exercises. Eat right, drink water and get plenty of rest.

Over time (6 months), you'll see which areas need more work. For me, my shoulders needed more focus so I added other exercises.

Let's face it, at 40, I look better than I ever did.

So, to summarise, do:
-deadlifts
-squats
-bench presses
-pull ups
-dumbbell bent over rows
-overhead shoulder presses.

Twice a week, 3 x 6 reps.

"But what about ab work?" All of those exercises work the core.