Yes that's normal. The Thargoids are present in the Witch Head nebula since the "The Enclave" Interstellar Initiative.
Non-human signal sources with threat levels up to 9 is normal.
The Enclave
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Non-Human Signal Source
Not to be confused with Nonhuman Signature. Main article: Unidentified Signal Source A Non-Human Signal Source is a type of signal source that contains one of several possible Thargoid encounters dependent on its threat level. The threat level varies from 0-9. Non-Human Signal Sources spawn...
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