I have tried to invent a form of hyperdimensional physics. Start with two branes colliding. As you would know the flat earth folk get laughed at but not so the uni-centrists. There is a question of did we get all the details just right.

I am an ex-government employee and so not to be trusted (I sold train tickets), also recently struggling to answer you (my cat the 'alien') didn't want you to know this. No one considers that if two branes collide that the discharge must start from a side. Since there is no empty space it must be created which is very energy intensive, a sort of Tesla space if you like.

Aliens, I don't know. Intelligent beings, well not the humans anyway. Time travel is just round the corner and if you are getting visits from future humans consider them as good as dead. As stiff as the time line is if in quantum two time like line tenth dimension only one final existence is possible.

The cases are an intelligent species stops stupid humans from accessing time, probably already too late. The damage done to the mind local and global is incalculable. Case two humans are really smart and accept whatever carnage they exist in and elect to go forward. Case two only works with the almost total destruction of humanity on a regular enough basis because they just can't be trusted. Case three and the most likely, humans become smart enough to ensure total annihilation of the species which incidentally makes it finally safe for the rest of the universe.

So the short answer is if a species or lifeform in our timeline that genuinely valued its life found humans to be too dangerous. It could be forgiven for the total and utter destruction of all humanity after all we are most likely to do it to ourselves anyway. Just for argument lets say the sun is a large complex and sentient thing or the earth Gaia. Nano grey goo is not the sort of stuff to sneeze at you know.

Any peace mission sent back would be a failure as information corrupts in time brought back before its source and potentially changes (read destroys) the future it came from. And with quantum time like lines any present information corrupts the further forward in time it is available and preserved to be thought on.

Information must give knowledge, knowledge must lead to wisdom, wisdom creates new information or rewrites the source to remove it from corrupting factors. The nature of humans must be measured by group which means there is no hope by any standard unless you do as I do and hope for divine intervention