Litecoin is copy paste of Bitcoin.
Litecoin promises many cool features in the future, privacy second layer solution, credit cards.
But everything what can be built on Litecoin could be also on Bitcoin.
So Litecoin is only testing platform for Bitcoin new upgrades.
Couldn't put it any better than this. Litecoin was one of the first copycat coins that plagiarized the idea behind Bitcoin, and still came to be regarded as one of the top altcoins. Just like you said, technically Litecoin has zero advantages over Bitcoin. The only thing I can think about is the transaction fee, but even in that aspect I don't think that there is a major advantage in using LTC over BTC.
My take on Litecoin is very simple. From 2011 to 2015, Litecoin remained as the no.2 cryptocurrency, despite its many weaknesses. Eventually, it was overtaken by other altcoins such as Ethereum and Ripple. Let's just admit that the peak period is over for Litecoin. It helped many investors to become rich (including me), but now it has hardly any future potential.