newcomer

[Fredoon]

Dear native English speakers
Could you do me a favor and tell me if the following use newcomer correctly?
Many problems besetting today's people are not newcomers, but they have remained unsolved for centuries and seemingly still will exist in the future.

 

[emsr2d2]

Dear native English speakers Hello (You're not writing a formal letter so there's no need to open with "Dear". We have several non-native speakers here whose help is invaluable.)
Could you do me a favor and tell me if the following uses "newcomer" correctly?

Many problems besetting today's people are not newcomers, but they have remained unsolved for centuries and seemingly still will exist in the future.

It's an unusual use of the word but I can't say it's wrong. However, we normally use "newcomer" to refer to people.
Did you write that sentence yourself?

 

[Fredoon]

Thank you. Yes, I did. Actually, according to the Longman Dictionary, I used "newcomer" for things:

 

[emsr2d2]

Thank you. Yes, I did. Actually, according to based on what I found in the Longman Dictionary, I used "newcomer" for things.

If you say "According to the Longman Dictionary, I used ...", it means that something in that dictionary states that you used "newcomer" for things. That's definitely not the case. I'm pretty sure you're not mentioned in the dictionary!

 

[teechar]

Many problems besetting today's people

That is clumsy, especially "today's people".
Try something like:
"Many problems which people face these days are not new".