Here are three different performances of your Handel passage chosen at random from Youtube. You will notice they are all different:
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The reason is that Baroque music was not meant to played exactly as written. The performer was more or less required to interpret the ornamentation according to his own taste, and it was quite normal that he would never perform it the same way twice. Consult any scholarly work on Baroque performance practice.
Get to know the ornamentation style through various listening, reading, and study, then play accordingly, with your own ornamentation choices, like in these videos; or simply imitate any good player's ornamentation.