He's talking about how the "magical", naive, imagination-based ways we understand things when we are young colour the way we perceive them we we get older.
Even if we know, rationally, that the way we used to think about something was incorrect, and conflicts with what we know to be true as adults, we don't discard those old ideas entirely, and they remain internalised to some extent:
The point is that all the earlier versions, even those as patently false as the one with the stork, are not discarded completely. Something of them remains in us; they mesh with succeeding versions and somehow continue to exist
I actually think it's at least a little more profound than you give it credit for.
To each his own. Comparing his ideas to software development would not be my first instinct, but I don't think level of abstraction is what he was going for. A closer analogy would be where there are many different implementations of an interface that run concurrently and then have their many outputs fused back into one single output. But that reads more awkwardly than the way Lem said it :)
I like Lem but sometimes his complex grammar and vocabulary doesn't add any value. I think it's better to describe (relatively) simple things in simple language. Lem tended to phrase everything that way.