You need to read ALL of Isaiah,Chap.7 to put Isaiah 7:14 into its’ proper context.
You cannot pick and choose from the Hebrew Scriptures.
Moses was the first prophet, so to 'fully' understand Isaiah, the reader must/need begin with the In the beginning, God created the heavens and earth....
2 AND the earth 'became' without form, and void; and darkness was upon the face of the deep.
AND the Spirit of God moved upon the face of the waters......
Isaiah 45:15 Verily Thou art a GOD That hidest Thy-self, O God of Israel, the Saviour.
16 They shall be ashamed, and also confounded, all of them: they shall go to confusion together that are makers of idols.
17 But Israel shall be saved in the LORD with an everlasting salvation: ye shall not be ashamed nor confounded world without end.
18 For thus saith the LORD That created the heavens; God Himself That formed the earth and made it; He hath established it, He created it not in vain. He formed it to be inhabited: "I am the LORD;
and there is none else.
Isaiah and the other prophets wrote down what God's plan was from the beginning, and over and over again we are told about a Saviour, and everlasting salvation.