The English "j" sound is a voiced postalveolar affricate, transcribed in the International Phonetic Alphabet as /dʒ/. It is indeed the voiced counterpart to the voiceless "ch" sound /tʃ/.
The phones [dʒ] and [tʃ] are both fairly common, as far as affricates go. Voiced obstruents are generally less common than voiceless ones, and [dʒ] is less common than [tʃ]. I found the following article that describes some phonetic reasons for this tendency for sibilant affricates in particular: Phonetic explanations for the infrequency
of voiced sibilant affricates across languages. Nonetheless, [dʒ] is still not really rare.
In fact, it may even exist in several of the languages you mentioned, depending on the variety spoken, and how you define what you mean by "the English j sound."
For German, Wikipedia says
/ʒ/ and /d͡ʒ/ do not occur in native German words but are common in a
number of French and English loan words. Many speakers replace them
with /ʃ/ and /t͡ʃ/ respectively (especially in Southern Germany,
Austria and Switzerland), so that Dschungel (from English jungle) can
be pronounced [ˈd͡ʒʊŋl̩] or [ˈt͡ʃʊŋl̩]. Some speakers in Northern and
Western Germany merge /ʒ/ with /d͡ʒ/, so that Journalist (phonemically
/d͡ʒʊʁnaˈlɪst ~ ʒʊʁnaˈlɪst/) can be pronounced [ʒʊɐ̯naˈlɪst],
[d͡ʒʊɐ̯naˈlɪst] or [ʃʊɐ̯naˈlɪst]. The realization of /ʒ/ as [t͡ʃ],
however, is uncommon.
So [dʒ] does exist for some speakers of German, although it sounds like it can be considered marginal. (I don't know if this is a perfect analogy, since I don't speak German, but you might compare its status to /x/ in English words like loch and Bach.) The voiceless sound [tʃ] (usually written tsch) has a more stable pronunciation and is more common, but I've read that even [tʃ] is rare in German compared to other sounds such as [ts].
For French, [dʒ] and [tʃ] can equally be said to exist or not exist.
Normal native French words do not have either of these affricates, since historically they were simplified to the fricatives [ʒ] (usually spelled g or j) and [ʃ] (usually spelled ch). However, due to the influence of foreign languages, phonetic affricates [dʒ] (spelled dj) and [tʃ] (spelled tch) do exist in some modern French words, names and expressions, such as djaïn "Jain" and tchao "bye." It's possible that phonologically these can be considered consonant clusters composed of a plosive phoneme and a fricative phoneme, like /ps/ in psychologie or /gz/ in xylophone.
For Spanish, the phoneme /ʝ/ often sounds similar to English /dʒ/. Wikipedia's article on Spanish phonology says that in standard Castillian, this phoneme is realized as an affricate [ɟʝ] after a pause or after a nasal or lateral consonant. This is very similar phonetically to [dʒ], and I believe some Spanish dialects do just use [dʒ] (in others, [dʒ] has been changed by lenition to [ʒ], which may then be devoiced to [ʃ]).