Evangelicals do believe that Scripture as the apostles wrote it is infallible.
What about what was written by Luke and Mark? They were not apostles. According to your logic, these were not inspired writers. What about Hebrews? According to your logic, it should be counted as non-inspired.
Ignatius notes a difference between his authority and that of the apostles, when he writes:
"I do not issue orders like an apostle.” Epistle to the Trallians, 3)
You have taken that quote entirely out of context. Here is the fullness of the section:
I know that you possess an unblameable and sincere mind in patience, and that not only in present practice, but according to inherent nature,
as Polybius your bishop (Singular) has shown me, who has come to Smyrna by the will of God and Jesus Christ, and so sympathized in the joy which I, who am bound in Christ Jesus, possess, that I beheld your whole multitude in him. Having therefore received through him the testimony of your good-will, according to God, I gloried to find you, as I knew you were, the followers of God.
For, since you are subject to the bishop as to Jesus Christ, you appear to me to live not after the manner of men, but according to Jesus Christ, who died for us, in order, by believing in His death, you may escape from death. It is therefore necessary that, as you indeed do, so without the bishop you should do nothing, but should also be subject to the presbytery, as to the apostle of Jesus Christ, who is our hope, in whom, if we live, we shall [at last] be found. It is fitting also that the deacons, as being [the ministers] of the mysteries of Jesus Christ, should in every respect be pleasing to all. For they are not ministers of
meat and drink, but servants of the Church of God. They are bound, therefore, to avoid all grounds of accusation [against them], as they would do fire.
In like manner, let all reverence the deacons as an appointment of Jesus Christ, and the bishop as Jesus Christ, who is the Son of the Father, and the presbyters as the sanhedrim of God, and assembly of the apostles. Apart from these, there is no Church. Concerning all this, I am persuaded that you are of the same opinion. For I have received the manifestation of your love, and still have it with me, in your bishop, whose very appearance is highly instructive, and his meekness of itself a power; whom I imagine even the ungodly must reverence, seeing they are also pleased that I do not spare myself. **But shall I, when permitted to write on this point, reach such a height of self-esteem, that though being a condemned man, I should issue commands to you as if I were an apostle? I have great knowledge in God, but I restrain myself, lest, I should perish through boasting. **For now it is needful for me to be the more fearful; and not give heed to those that puff me up. “For might not I write to you things more full of mystery?..thought I am acquainted with these things, yet am I not therefore by any means perfect; nor am I such a disciple as Paul or Peter. For many things are yet wanting in me, that I may not fall short of God.” Epistle to the Trallians, 5)
St. Ignatius was saying that he was not writing commands as an apostles so as not to perish through boasting. It does not mean that he couldn’t have done so.
If you are going to quote the ECF, then be advised that we are not going to let you pull things out of context.