There are a number of factors that make a disaster more "newsworthy", or likely to be famous.
Specifically with regards to the Titanic:
- it was sailing from the UK to the US, both English-speaking countries, causing it to be more famous in the English-speaking world.
- it was said to be "unsinkable", but sunk anyway. This makes for a better story.
- yes, the fact that it was in peacetime made it more shocking than something taking place in WWII. That isn't because the lives were inherently "worth more", but simply because unexpected things are more shocking and memorable than expected things. During war, we become desensitised to tragedy.
- Robert Lord's book A Night to Remember sparked renewed interest in the disaster in the 1950s.
- the discovery of the wreck in the 1980s sparked further interest, including James Cameron's film.
Our perspective of history is not objective, or even very good. We are naturally biased towards our own countries. I know far more about British history than any other country. Second is the US, which shares a common language and has been the dominant global power my whole life. Speaking "objectively", I should know as much about French, Russia, or Chinese history, but I don't. I know even less about precolonial America, Africa, India, or Australia. And temporally, I know much more about the 2010s than I know about the 1910s or 1810s. That's basically an unavoidable part of being a human.