There are multiple reasons, even more than you've given OP.
The most important are that it's widely known and recognized in the field that's new and unrecognized as a whole. Maybe 1 of every 100 people in the world has heard of BTC and knows what it is, while maybe 1 out of 500 knows some other altcoins. I don't know the real numbers, i'm only estimating here, but I know people who are tech savvy and they know barely anything about BTC and completely nothing about altcoins.

This bitcoin seems really very impressive to me. This bitcoin is the king of all coins. Bitcoin prices are much higher. It will gradually get bigger in size. Many people of the country have benefited financially using this Bitcoin. Even this Bitakayena's work has benefited a lot financially. It has changed my life. Because of this, Bitcoin has become very influential.

Bitcoin is a most dominant because bitcoin is a biggest crypto currency because this is the first crypto currency invented in the whole world.

Because Bitcoin is honest and real in developing its working procedures, as well as systems, as well as all of its programs.
Bitcoin has a target and also a dream to keep trying so that all its users and also the entire community in this world can be successful and also can feel happiness in their respective lives.
Bitcoin is becoming dominant today because there are already many people who have followed Bitcoin's work procedures, which they have felt and which makes them more confident of all these programs from Bitcoin for them to work and become the result of their fortune in the economy their respective lives.

I think bitcoin is very popular and bitcoin is indeed the first successful coin to succeed in cryptocurrency and until now bitcoin remains the highest value and price compared to other coins that keep popping up, that's in my opinion

I believe that the reasons you stated all are contributing factors to Bitcoin's dominance. In the Cryptoworld, Bitcoin is the most popular among them all. This, coupled with the fact that it was the first to come and that people trust that it can sustain for long makes people rather prefer buying Bitcoin to the others.

Because of BTC's structure, lack of pre-mining and the fact it was the first into this space, BTC is by far the most decentralized major cryptocurrency. Nodes are running all over the world and this has created a highly secure network that has never been hacked. By contrast, when Ethereum got hacked, it ultimately rolled back ETH transactions, which showcases just how different (and centralized) it is compared to BTC. ETH founder, Vitalik, even promises to throw countries or their leaders off of the ETH network if they "do evil". Do you want a crypto where one person (Vitalik) gets to decide what it means to "do evil" and which transactions don't get to go through as a result?

Like ETH, many of BTC's competitors are centralized, which means there are fewer pressure points to be exploited by hostile actors. The CEO or founder could exit-scam, or release all the coins in escrow, or a nation-state could bribe/blackmail the person/ppl in charge into making changes to the protocol that benefit them, etc. With Bitcoin, there's no one in charge. There's no one person or hardware that it's too reliant upon. There are fewer pressure points, which makes it far more secure.

The 2nd and 3rd question is right. Bitcoin was the first coin introduced in the market and believed to be the pioneer of the innovation. It gained popularity afterwards because of its function to be used as an alternative for transactions.

The question of being the current best, is now in question.

Bitcoin is the predominant digital currency today. Because bitcoin has high security. Bitcoins are trusted by many and invested in. Many countries like Japan, Korea are creating the best conditions for bitcoin activities. They want to make bitcoin an international currency.