The Greek of Mk.3:17 reads (transliterated) "Iakobon" (Ἰάκωβον). James 1:1 begins, "Ἰάκωβος," no difference other than the terminal letter indicating the case. These are two completely different people, of course. The first, the brother of John and both of them apostles, is different from the author of the General Epistle--who is either the half-brother of Jesus (James of Jerusalem) as most think; or the second of the apostles to go by the name James, son of Alphaeus.
Hebrew for Jacob reads (transliterated) "Ya'qov" (יַעֲקֹֽב) Gen.25:28. It can be helpful in NT translation to render the OT person in a unique manner, alerting the reader to the OT reference, as in Rom 9:13, "Jacob (Ἰακὼβ) have I loved." Sometimes, we inherit a tradition that has made little translation-adjustments to certain names for the benefit of the reader to aid in telling literary personages apart. Otherwise (and this is actually a case in the KJV) we have TWO Jesus' in Hebrews: our Lord most of the time, and one we usually call "Joshua" (Heb.4:8) the OT general--potential confusion and misunderstanding that most modern translations avoid. Some KJV readers probably have never connected 4:8 to the end of the previous chapter rehearsing Israelite history, and think the Savior is the direct referent in that verse.
As Lane already pointed out, "James" is a suitable English rendering or equivalent name for any of the OT or NT persons, though it departs from the sound of that name in either original language. Jacob's Hebrew name contains one letter with two different sounds associated (b,v) and a "guttural" letter with no English (or Greek) equivalent). Greek doesn't have a "v" sound, so goes with the "b." "Jacob in Hebrew has a different "k" sound to what we're used to, a back-of-the-throat bark of sorts (Hebrew also has a more "conventional" sounding "k" letter).
There isn't anything more "sanctified" or preferable about trying to pronounce a personal name--not even the divine Name--in the sounds of an original language. Not unless someone has told you, "I wish you'd try to pronounce my name as if you were a native speaker of my (or some other) language." Shouldn't we just do our best with the letters and sounds we have (and are used to)?
The name "Saul" is adjusted to "Paul" not as if a consonantal move were made, similar to the v-to-b in Jacob. No, Paul is an alternate name, as "Peter" was to Simon, only with a rhyme. Paul means "little," and is unrelated to the etymological meaning of "Saul" in Hebrew [maybe there is some irony intended, since Saul was head-and-shoulders taller than most Israelites].
"Santiago" contains both "Saint" and "Iago," only the latter part from the Hebrew, "Yako[v]" and Greek, the hard central consonant softened somewhat (?) for a Spanish pronunciation. In this case, one has to "burrow" halfway into the name itself to discover the verbal connection. The fact there are multiple NT figures who have the same name might encourage some distinction in translating, and the more likely if one expression has been used as a traditional and unique identifier, as in the case of the writer of one of the NT letters.
An argument may be made that the result is more, not less, confusing. But generally, we just accept that we've been born at a particular time and place, and inherit the many and various aspects of our particular language. The more of other languages you know, oftentimes the bigger picture you gain.
