It looks like you're right :
After a few more days passed, and still not seeing anything new in my region, i decided it was time moving away to seek the challenge of the game because at that point it looked more and more than in current Ark region are difficulty "capped" (featuring then their own set of dinos that correspond to the region difficulty level with no higher difficulty dino ever having a chance to come or spawn in easy regions) and not time related
Meaning all the time i spend making my base being useless as no dangerous dino would come.
Took my boat and decided to explore relatively far in the south west of my region.
After some time following the river that is between the mainland and the big southwestern island, i saw some funny water battle between what looked like tall ducks (those guys that leave those nice and rare "Organic Polymer" as loot from skinning them, the material that is usefull in crafting the ghillie suit armor) and inflated pirhanas
And it looks like the ducks actually had the upper hands as i started to see several pirhana corpse floating.
I had to help those ugly fishes, not because i like them but because the "Organic Polymer" from the ducks is something good to fetch.
Resuming course, after more time i ran into what looked like a raptor but slightly smaller, so no idea what it was called, but it was running on the land without a care for me or the other animals around. Then more interesting i spotted a big (well slightly bigger than a raptor) threat, a carnotaurus that looked much meaner and bigger than i thought. And that guy really meant business because it killed several small river banks animals (no idea what they are, they exist around my base sometime , some gecko/lizard type thing that are a bit bigger than a dodo)
As i had a lot of tranq arrows, was on my boat , i decided maybe it could be a good idea to try to tame that ugly big bad for additional protection on future away explorations.
After more than 6 arrows, the thing simply didn't stop, it jumped into the water, swim to my boat, jumped on it, followed me after i jumped in the river trying to save my life while still shooting arrow.
In the end the carnotorus probably had a dozen of tranq arrow in his head and throat, but he never slowed down and destroyed my character, i managed to last for a while as i had upgraded my health a lot but still got eaten.
It was a fun adventure coming back to my corpse and boat, using my big turtle as a boat to avoid long walking time