Hey, It's perfectly okay as long as the 19 year old person is self conscious, confident, have enough means to survive (as in stay and eat). Having said that, let me add that Himachali people are extremely warm hearted and welcoming 😊 I would further suggest that if you want to explore the raw Himachal Pradesh, you could go on a trek through some or the other trek organizing agency. That way you would be solo as well as you would be with a group of people. You could DM if you would want to know more about treks, I might be able to give you a few leads 😊 Happy tripping!
Keep a smile and approach. Everyone will help. You might find a lot people higher than the altitude in Manali, Shimla, Dharamshala area. (IF you know what I mean) but story is a lot different on the other side of mountains in Kinnaur and Spiti
Yes it is absolutely safe! being a female travelling myself I have been travelling solo to himachal since my early twenties. I would suggest you to stay at hostels since you get to meet a lot of interesting people in addition to seeing amazing places
As long as you are aware of your surroundings everything is cool. Just be vigilant while planning your stay and places your wish you see. If you need any details about Himachal Pradesh feel free to message me here or dm me on insta @curly_saga_ happy to help! 🌺