Why does Android use Java?

I think it's right to ask Google, but I'm posting a question here because I'm curious about other people's opinions.

The main development tool for Android is Java. I wonder why. I mean, isn't it too slow to interpret code on a mobile device? When introducing Froyo, Google said that the JIT compiler creates applications 2 to 5 times faster, but is this the same as using Java and more than 2 times slower?

Of course, we know the system stability and many advantages of using Java, but the serious performance degradation of using Java makes us wonder why we use Java.