Which facts? There is no any single country in Europe where I1 is in majority.
Even in Scandinavian countries R1 (combined R1a and R1b) is more numerous than I1.
The highest number of I - but in this case mostly I2, not I1 - is in the Balkans.
Obviously I (both I2 and I1) belongs to pre-Indo-European folks of Europe. But so do few other haplogroups.
In general there is scarcity of data on prehistoric Y-DNA, very small samples. There is more data on mtDNA but it is harder to interpret.
I compiled data on ancient Y-DNA from two websites (Eupedia and Ancestral Journeys), and it still looks quite miserable:
http://www.ancestraljourneys.org/adnaintro.shtml
http://www.eupedia.com/europe/ancient_european_dna.shtml
As you can see scarcity of data can lead to wrong conclusions.
For example we know that I haplogroup did not disappear from Europe after the Bronze Age, even though this chart suggests this.
I wonder what was that F* from the Neolithic period - ancestor of which haplogroup or haplogroups?
F is ancestral to G, H, I, J, K (any of these could split from those Neolithic F*s, right?). K is ancestral to R1, but also to several other HGs.
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Obviously apart from I haplogroup, also for example G haplogroup in Europe is pre-Indo-European:
I don't see anything contradictory in supposing that I1 could have been one of the markers present in the early Proto-Germanic peoples.
Early Proto-Germanic peoples did not live in Scandinavia, but migrated to Scandinavia.
Scholars argue whether we can talk about Germanic language before migration to Scandinavia, or did it emerge in Scandinavia.
Anyway - Germanic is clearly an Indo-European language, despite its large number of loanwords from pre-Indo-European substrate. Vocabulary is not everything - for example English is counted as a Germanic language, even though it has a lot of words from Latin, French and other languages.
So people who brought Indo-European ancestral language of Germanic to Europe (including Scandinavia), were not of I1 haplogroup.
I1 belonged to pre-Indo-European communities of - mostly - hunter-gatherers. So did I2.
German has more non-IE words than any other European language (except for Basque, obviously)
I am sure that Hungarian, Estonian, Finnish, Turkish and several other Non-IE languages of Europe also have more Non-IE words.
you could almost say that Germans are the mongrels of Europe
Yes they are but isn't this due to their historically warlike attitude and assimilation of a lot of Non-Germans?
BTW - when I wrote about Germanic I wrote about all Germanic-speakers, not just Germans.
Of course I1 haplogroup is most numerous in Scandinavia, not in actual Deutschland.