It was too early for me to choose this news article as the discussion topic because it was too hard for me.
I really shouldn't have picked this article to use as the textbook because it was too difficult to begin with.
This article was too hard for me to use as the textbook.
〜しなければよかった、すればよかった、は
should have(過去完了), shouldn't have(過去完了)/had to 〜
例えば、アイスを食べなければよかった〜 I shouldn't have had the ice cream.
「この記事を選ぶべきでは本当になかった〜」
I really shouldn't have picked this article
「百万年早い」は、「恐れ多くも未熟だった」のような意味かと思いますので、
It was too early for me to 〜 のように、「私には〜するのは早すぎた」と言えます。
It was way too early で、とっても早すぎた、という意味です。
I am never that great. など、「私はそれほどすごくは絶対ないわ」など、落ち込んで恐縮して言えます。