Android was not aimed at blackberry. It was to be a completely new phone OS from the ground up and add extensive capabilities to the phone world over what the blackberry (the most popular phone at the time) could. Yes the G1 had a similar form factor to the most popular phone at the time and it wasn’t even the only form. It was a prototype that barely even sold. The Motorola droid was the most popular android phone when they actually shipped. Development problems and companies scared to gamble on a radical new product delayed Androids launch behind iPhones. Apple did a fantastic job of developing the iPhone in secret, knowing the Android was coming.