It is my understanding, and in my own study of these
passages that you mention, that in 1 Tim 1:15-16, the
Apostle IS saying that he was chief or "first" in
rank/number...first in line.
Like you said, the greek word for "chief" and for
"first" is the word "protos", which we get our english
word "prototype". That word is used when they make
robots or new cars...it's the first model that all the
rest are built like.
So yes, when Paul uses the word "chief", you are
correct, he is saying not that he is the worse, but
that he is first in rank, first in succession, at the
head of the line, the pattern of all that are saved
eternally by grace thru faith in the shed blood of the
Lord Jesus Christ plus nothing in the present
dispensation of grace.
Now onto the passage in Romans 16:7...Salute Andronicus
and Junia, my kinsmen, and my fellowprisoners, who are
of note among the apostles, who also were in Christ
before me.
It is my understanding from scripture that the Apostle
is not saying that these people are members of the Body
of Christ, but that they were members of God's "church"
before the Body was revealed, that is, the Messianic
kingdom church of Matthew thru early Acts.
These people who were "of note among the apostles" and
Paul's "kinsmen" were JEWISH saints who trusted Jesus
as their Messiah way before Paul came on the scene.
Early in Paul's ministry, the Lord Jesus used some of
those Messianic kingdom saints to help Paul labour in
getting this new program out (Barnabus for example).
Just because their kingdom program was on hold does not
mean that God did not use them to serve Him until they
all died off, and many of them helped the Apostle early
in the book of Acts.
As far as them being "in Christ before" Paul, that just
shows that they had faith "in Him". Even in the kingdom
program to Israel, the Lord made it clear that those
members of His little flock were saved "in Him".
Isaiah 45:17...But Israel shall be saved in the LORD
with an everlasting salvation: ye shall not be ashamed
nor confounded world without end.
Isaiah 45:25...In the LORD shall all the seed of Israel
be justified, and shall glory.
John 6:56...He that eateth my flesh, and drinketh my
blood, dwelleth in me, and I in him.
John 14:20...At that day ye shall know that I am in my
Father, and ye in me, and I in you.
1 John 4:13...Hereby know we that we dwell in him, and
he in us, because he hath given us of his Spirit.
1 John 5:20...And we know that the Son of God is come,
and hath given us an understanding, that we may know
him that is true, and we are in him that is true, even
in his Son Jesus Christ. This is the true God, and
eternal life.
So ALL true believers are "In Christ" whether in
the kingdom program of time past and the age to come,
or today in the Body of Christ in the dispensation of
grace, ALL who trust Him are said to be "in Him",
although we today are in His "Body" which was a Mystery
until revealed to and thru Paul.