The first paragraph of the שמע is found in yesterday’s Parsha. Aside from the first line being a strong affirmation of faith, the first paragraph has seven important Torah laws.
The words ה׳ אחד , teaches the Oneness of Hashem. This refers to His uniqueness like nothing in the universe.
We are commanded to love Hashem learned from the word, ואהבת.
The ושננתם לבניך teaches that we must study Torah on a regular basis. How are we to teach our children, if we don’t study ourselves?
The recitation of the שמע in its proper time in the morning and evening, is also a Torah commandment.
The תפילין של יד and תפילין של ראש, are considered as two separate Mitzvot.
And the commandment to have Mezuzot on our doors and our gates, is also a Torah commandment. So we see that the שמע has an added importance because of the seven Torah laws, it contains.