Plagiarism
That was his response.
Honestly, I think that this is an unfair comment on a story. Plagiarism is, ultimately, an academic offence and there's a big difference between plagiarism and copyright infringement.
If you write an academic paper and you reference an idea that you didn't come up with - let's call it idea Y - then if you fail to give credit to person X for idea Y, then you will commit plagiarism.
However, in fiction writing, an idea cannot be copyrighted. There is no plagiarism for a similarity of ideas and ideas that you "borrow" or are "influenced by" do not need to be attributed or avoided. For example, if you look at "Dune" we have an aristocratic person (Leto Atreides) going to take up a position he sort-of doesn't want and then he gets executed part-way through the book. Then compare that with "Game of Thrones" where we have an aristocratic person "Ned Stark" going to take up a position he sort-of doesn't want and gets executed at the end of the book.
Aside from the setting, and a few consequential details, Ned and Leto's stories are basically the same. However George RR Martin didn't plagiarise Frank Herbert. (Even if when I read "Game of Thrones" in 1996 I saw Ned Stark's execution coming from when he accepted the job of "The Hand".) No more than Terry Brooks plagiarised "The Lord of the Rings" when he wrote "The Sword of Shannara" (and before I get any criticism or complaints - I'm not alleging that he did and I'm not saying that he did.)
What is different is the execution of the plot. And that is the fiction writer's saving grace over the academic.
So long as you do not directly copy from another writer's work then you are fine. Sure, you can be criticised by readers for your similarity of plot or character or idea (I've just done it). But so long as they're not absolutely identical then it's not copyright infringement. It's not something you should be worried about.
Oh, and everyone borrows some version of FTL and teleportation from someone who has already written about it - I mean how would you write sci-fi without the concept of FTL that you failed to invent because someone thought of it before you. Honestly, I wouldn't worry too much about that if I were you.
Equally, I haven't read your story, so I don't know - The best advice I could give it that you should just post your 75-word story and let people look at it. It's probably fine.