The short answer is that you are right to question the workbook's black-and-white logic. Both versions could be generated by native speakers, but the first probably sounds better and means something a bit different. It also pertains to a higher register thanks to the inversion.
The problem is that we can't tell you why your workbook requires a particular answer and forbids a different one. Only the authors of your workbook can answer that for you. But you shouldn't much trust any workbook that pretends that there is such a a thing as a "Type II Conditional". That's a genuinely harmful misrepresentation of how English conditionals work. The only honest treatment doesn’t try to hide the fact that English has hundreds upon hundreds of combinations of tense, modal, auxiliary verb, and word-ordering in its innumerable possibilities.
Rewriting your two choices into more directly comparable forms, we see that the only difference is whether the protasis employs a past perfect construction (sentence 1) or whether it employs a normal past tense (sentence 2):
- If he had not made a good impression in his early life, he would not be the star he is today.
- If he did not make a good impression in his early life, he would not be the star he is today.
There isn't a right and wrong here: both forms can be trivially found in the speech and writing of native speakers. The first is probably preferred because it better conveys the counterfactual nature of the proposition under consideration.
The second is using a “real past” not a hypothetical one, so may or may not be slightly different in nuanced meaning in the mind of a native speaker. But quite possibly it means the very same thing to most people.
The inversion choice ("had he" rather than "if he had") presented in your original workbook is of a higher register than the uninverted version. That makes a difference, too. Inversion of this type is far more common in crafted literature or formal oratory than in casual, spontaneous speech.
Beyond that, there’s really not much to talk about here. Both things happen, and your workbook is teaching you facile lies to help steer you clear of many ungrammatical possibilities you might otherwise tumble into.
