Writing tip, week 1!
nothing wrong with using the word ‘said’ repeatedly. I was shocked by this too, but apparently using a wide set of different words (murmur, growl, mumble, declare, retort, explained) can confuse the reader.
As you can see even in classics, they tend to use only 'said' or 'asked'.
Of course, you can use the others but it is better to stick more to 'say'.
Hope you take this tip into consideration! :))