The problem Starmer has, and Corbyn had in 2019, is he has no actual vision to explain why he wants the things he wants.
In 2017 Corbyn had a vision and policies that flowed naturally from that vision.
In 2019 he had a random grab bag of policies that looked expensive, and worse, made no sense in the context of any coherent vision.
Labour needs to go back to the beginning, ask "what do we want", preferably in a form that can be expressed in a sentence, at least in the outline of terms, and then build on that.
Like "Building bridges of understanding across the United Kingdom" or something